The present invention relates to a golf club head where a curvature is given to a face surface, more particularly, to a golf club head in which a loss of carry due to reduction of a launching angle is prevented and variance of carry due to difference of a ball striking position in an upper/lower direction is suppressed.
Generally, the curvature, which is called a roll, that curves in the upper/lower direction (a vertical direction when a golf club is held) is given on the face surface of a wood type golf club head. A roll radius is usually set to be constant across the entire face surface.
As described above, in the golf club head where the curvature of a constant roll radius is given to the face surface, a substantial loft angle at a portion lower than a center of the face surface is smaller. As a result, a struck ball did not rise as expected when the ball was struck at the lower face surface of the golf club head, which caused a problem of a carry loss. Specifically, in the case where the ball striking position is made at the lower face surface, although an initial ball velocity increases a little with a presence of the roll, a reduction of the launching angle influences more to the carry than the increase of the initial ball velocity.
Moreover, in the above-described golf club head, the carry at the lower ball striking position is insufficient. There has been a problem that variance of the carry became large when the ball striking position changed in the upper/lower direction.